Molten steel is produced in large furnaces and may thereafter be transferred into smaller vessels, such as ladles, for further processing. If the molten metal is to be delivered to a continuous caster, then it must be poured into the caster at the proper temperature. During the period between tapping the furnace and supplying the molten metal to the caster, however, the temperature of the steel may fall below the required minimum. The temperature of the molten steel must thus be raised to at least the minimum temperature, otherwise the steel will need to be poured into ingot molds. The temperature of the steel in the ladle can be raised by blowing oxygen into it, or by adding materials which produce an exothermic reaction.
Another important factor in making steel is to reduce the level of impurities, such as the level of sulfur. Desulfurization typically takes place in the ladle, prior to the molten steel being poured into the continuous caster. Lime may be introduced as a desulfurizing agent.
Lances have been used for supplying the oxygen used for reheating the steel, and for adding lime during the desulfurizing step. The lances have been limited to either reheating or desulfurizing, thereby requiring plural lances if reheating and desulfurization are to occur. Furthermore, oxygen injection lances are not suitable for lime addition, because the oxygen flow conduits are not sufficiently large for the required volume of lime.
The desire to reduce sulfur content to ultra-low levels, i.e. 0.002% or less, is growing. The ultra-low sulfur levels may be reached when lime is combined with aluminum oxide resulting from ladle reheating to form a calcium aluminate slag. The two steps involved, however, slow the process, thereby bringing about a need to improve efficiencies.